Field of the Invention
The present invention relates to image reading apparatuses configured to store simultaneously-read images of front and rear surfaces of a document as a single file in a memory.
Description of the Related Art
Techniques for simultaneously reading front and rear surfaces of a document and creating a single file are known. Japanese Patent Application Laid-Open No. 8-022536 discusses a technique for simultaneously reading front and rear surfaces of a document and creating a single file, and image data of the front and rear surfaces are stored in different buffers and the stored image data are encoded by an encoding apparatus.
More specifically, the image data of the read front surface is temporarily stored in a buffer memory 16 of a system main unit 3, and the image data of the read rear surface is stored in a buffer memory 10 having a capacity corresponding to one document page. Then, a data compression/decompression processing unit 17 compresses the image data temporarily stored in the buffer memory 16 and stores the compressed image data in a central processing unit (CPU) bus memory 15. Thereafter, image information about the rear surface stored in the buffer memory 10 is read by the buffer memory 16 and the data compression/decompression processing unit 17 performs data compression.
However, according to the technique discussed in Japanese Patent Application Laid-Open No. 8-022536, the image data of the rear surface stored in the buffer memory 10 is encoded after the image data of the front surface stored in the buffer memory 16 is encoded. This requires twice as much time for the encoding, resulting in a longer processing time. Thus, according to the conventional technique, encoding efficiency becomes low.
Furthermore, the technique discussed in Japanese Patent Application Laid-Open No. 8-022536 requires two buffers, the buffer memories 16 and 10 for separately storing the image data of the front and rear surfaces. Thus, the conventional technique also involves high cost.